Sound translating device



A ril 21, 19%,

M. 1.. M MURTREY ET AL SOUND TRANSLATING DEVICE Filed April 1, 1952 I INVENTQRS Du W111i. Cunnuzgham,

'MLeaiVcmrCreyg Patented Apr. 21, 1933 UNITED STATES PATENT OFFICE SOUND TRANSLATING DEVICE ware Application April 1, 1932, Serial No. 602,550

8 Claims.

Our 'inventionrelates to sound translating devices, and particularly ,to dynamic loud speakers having a moving voice coil mounted on the small end of a frusto-conical diaphragm.

In the design and manufacture of devices of the above type in accordance with the teachings of the prior art, difficulty has been encountered in properly securing the external circuit conductors or leads for the voice coil to the vibratory sound producing structure, in such manner that said leads and connecting means for the voice coil terminals may be free from contact with the pole pieces of the speaker field.

It has been common practice, heretofore, to staple the ends of external circuit leads directly to the cone diaphragm with the ends of the voice coil conductor being brought out from the coil and cemented along the cone to the stapled ends of the flexible leads. In another known construction the ends of the external circuit leads are soldered to eyelet terminals on the voice coil order that the eyelets might be spaced materia-lly from the top of the pole pieces at the air gap.

In general the above and other means for making connections to the voice coil have had various additional objectionable features from the standpoint of low cost for production, simplicity and ruggedness.

In still another external circuit lead arrangement fcriconnection with a voice coil, with which we are familiar, the external circuit connections have been made by securing the leads along the centering spider of the type secured externally to the moving coil and the outer pole piece. In a slightly different arrangement, the external spider, or spiders, has been made of metal and used as conductor leads for the voice coil.

It is, accordingly, an object of our invention to provide an improved and simplified means for making electrical connection between external circuit leads and the moving coil of a dynamic type of sound translating device, such as the voice coil of a dynamic loud speaker, independently of the diaphragm thereof and without interference with operatingmovement of the coil.

More specifically stated, it is an object of our invention to provide means for making circuit connections to the voice coil of a dynamic loud speaker, particularly of the type having a frustoconical diaphragm provided at the small end thereof, with an inside centering spider adapted to be fastened to the inner pole piece.

In accordance with our invention we have provided a novel form of terminal adapted to be secured directly to the voice coil form of a dynamic loud speaker for the purpose .of making external circuit connections to the voice coil.

The novel features that we consider characteristic of our invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in connection with the accompanying drawing, in which Figure 1 is a perspective View of a cone and coil form assembly of a dynamic loud speaker embodying our invention;

Fig. 2 is an enlarged side view in section, of the coil form and cone of Fig. 1, with portions thereof broken away to illustrate further details of construction;

Fig. 3 is a partially exploded view in perspective, and on a slightly enlarged scale, showing certain elements of the structure of Figs. 1 and 2, with one of the elements broken;

Figs. 3a, 4 and 5 are views in perspective of modifications of terminal elements shown in Figs. 1, 2 and 3, certain of the parts in Fig. 3d

being arranged in exploded relation to each other;

Fig. 6 is .a view in perspective of a modified form of our invention, with certain of the parts Referring to the drawing, a terminal clip I,

of the cone and along a portion of the coil form 3. A resilient centering spider ll, preferably of a highly collendered and dense fibrous material, is fastened to the inside of the small end of the cone and is adapted to be fastened to the inner pole piece 53 of the field structure shown in Fig. '7.

The terminal clip ,1, above referred to, comprises a piece of .thin metallic sheet material having an outwardly extending rim or soldering tab 13, adjacent the small end of the cone, and .a formed segmental flange 15 the contour of which has a radius of curvature corresponding with that of the coil form. This flange l5 fits snugly against the coil form and is secured in .place by means of a thin binder strip of fibrous material I9, such as a special grade of strong paper, with the aid of cement.

The ends of the segmental flange of the clip are preferably provided with deformable proj ections or upturned fingers I, as shown in Fig. 3. The binder strip l9, preferably in a single length although shown transversely broken, is provided with terminal positioning and spacing means such as pairs of slots 2| and 23 that fit over these projections or fingers on the flange of the clip, and is circumferentially cementedaround the coil form as shown. The pairs of slots 2| and 23 are preferably so spaced that if two clips are used, the clips will be diametrically opposite on the coil form when assembled. The projections or fingers H are clinched over on the strip to insure a firm mechanical connection therewith. During the assembly operation it is preferred that the terminal clips be placed on the binder strip [9, and the fingers I! clinched over, prior to their assembly on the coil form, thereby providing a convenient sub-assembly particularly adaptable for quantity production. The strip carrying the terminals is then Wrapped around the shank of the coil form between the end of the coil 5 and the small end of the cone or diaphragm. The strip serves the additional function of securely binding the cone fastening means 9 to the coil form.

If desired, the clips may be fastened directly to the coil form with the aid of cement, and subsequently the binder strip may be applied over the clip flange. Such a method should be employed in case another type of securing means, such as turns of thread, be used to bind the flange to the coil form. In these cases the fingers I1, when used, may be bent in the opposite direction in such manner as to securely clamp the clips directly to the coil-form. An arrangement of this nature is shown in Fig. 3a wherein the fingers I! on the ends of the segmental flange I5 are bent downward for projecting through slots 22 in the coil form 3 and adapted to be clinched over. With this construction it would be possible to dispense with the additional binding means such as the strip or thread above mentioned, relying on the cement and the clinching fingers for attachment.

The circular shape of the segmental flange portion materially strengthens the overhanging rim or tab portion l3 of the terminal in the assembly, as will readily beseen, insuring against bending strains under conditions of high amplitude of vibration of the voice coil. This construction is also free from local vibrations or rattles and provides a ready means for soldering external flexible leads 25 thereto at the point 21. The terminal leads 29 from the ends of the voice coil-5 are brought out for soldering to the point 21 under the binder strip l9 to one side of the terminal flange l5 as shown in dotted lines, Figs. 1 and 2.

In the foregoing structure the level of the flange l5 and binder strip, etc. is preferably no higher than that of the coil 5, and the rim or flange l3 of the clip is remote from the coil as shown. The above construction insures that the moving coil structure and all of its attachments are free of the pole pieces at the air gap, under all conditions of movement.

Referring to Fig. 4, we have'shown a slightly modified form of the terminal clip insofar as the central portion of the clip including the segmental flange I5 thereof in Fig. 3 has been cut away, leaving a ,pair of short flange portions 3| to provide in effect a two-point support, in order that the terminal clip may, for production purposes be adapted to fit a number of coil forms of different diameters. As in Fig. 3 the flange portions are preferably provided with deformable projections for clamping purposes.

Referring to a modified form of terminal clip shown in Fig. 5, we have illustrated a construction adapted to receive the end of the flexible conductor 25 having'an insulated covering 33. In this form the soldering tab l3 of the clip is provided with a bifurcated end comprising a pair of bent over elements 35 and 31, the former of which is adapted to clamp the bare end of the external lead 25 as well as the end of the voice coil conductor 29, for soldering, and the other of which elements is adapted to firmly grip the flexible conductor over the end of the insulating covering 33.

In the modified form shown in Fig. 6 a simplified terminal member is used, this form being adapted for inexpensive small sized speakers having light weight diaphragm and coil structures, and where the requirements of rigidity are not so severe. In this form the terminal clip comprises a soldering tab portion 39 having one end adapted to receive the conductor terminals and the otherend 4| bent at an angle that is preferably greater than a right angle, the extreme end of this angular portion having a deformable projection or an upturned finger 43, adapted to be clinched over on the securing strip 45 as in the above case. The securing strip is provided with opposed notches or openings 41 and 49, re-

spectively, in the side edges thereof, for cooperating with the bent portions of the clip for spacing and securing the terminals in proper position as in the above instance.

Referring to the complete loud speaker assemdescribed are shown in theirassembled relation with a field yoke and coil structure 50. The yoke comprises a U shaped member 5| of magnetic material having an inner pole piece or core 53 secured thereto at the bottom of the U by a riveting operation. A pole piece or yoke plate 55 is fastened to the outer ends of the U, preferably by fillet welding at 51. The field coil 59 is held in place on the core. 53 by means of a shading ringGLof low resistance non-magnetic material that is retained on the core by a press or shrink fit. The yoke plate 55 is provided with the usual circular opening 63 concentrically surrounding the core and forming therewith an annular air gap in which themoving coil-,5 is adapted to vibrate.

The outwardly extending arms 65 of the yoke plate are bent forwardly,'as shown, for the purpose of attaching a pair of metallic annular rings .55 bly in Fig. 7, the cone and coil assembly above 61 and 69 for supporting and protecting the base of the diaphragm or cone 1. The rings are preferably held together by rivets 1|, and the ring 61, adjacent the ends of the yoke plate, is secured thereto preferably by welding.

We have found it convenient to mount an input voice coil transformer 15 and its housing 16 on one of the extending arms 65 of the yoke plate. Accordingly, the arm is provided with a plurality of punched holes at 13, and a pair of cooperating fingers are formed on the transformer housing and adapted to be extended through the holes and clinched over, thereby providing a convenient and compact assembly of the transformer and speaker structure. A terminal board 14 of insulating material is supported by and between the transformer 15 and the yoke plate extension 65, and carries a pair of spaced soldering terminals 8| for the leads from the transformer and a pair of voice coil and terminals 82 for the field coil. Only one terminal of each pair of terminals is visible in the drawing, the other terminals being hidden from view by the transformer. One of the external flexible conductors 25 is brought out directly from the diametrically spaced terminal clips on the coil form to one terminal of the pair of terminals 8| on the terminal board on the speaker frame in the manner shown. The other conductor 25 (not shown) extends to the terminal 8| which is disposed at the opposite side of the transformer.

As will be seen from the foregoing, there is provided a light weight, durable means for making connection between the moving coil of a dynamic speaker and an external circuit. The particular terminal connections employed are of such nature that there is a minimum of change necessary in the usual preferred arrangement of parts, in order to provide the improved connection, and the arrangement and construction of the connection means are such that the latter in no way interfere with the operation of the loud speaker even under maximum amplitude of vibration of the coil form and diaphragm.

It is preferred that the support points or terminals 8| on the board be so positioned that the conductors 25 from the moving coil terminals l3 lie toeither side of the arm 65 of the yoke plate. As shown, the terminals 8| and. the board 14 are in such a position that the conductors 25 lie substantially in a plane at right angles to the axis of vibration of the moving coil, although there can be considerable departure from this position.

Although we have shown and described certain embodiments of our invention, we are fully aware that many modifications thereof are possible. Our invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the appended claims.

We claim as our invention:

1. A dynamic loud speaker comprising a frustoconical diaphragm and a moving coil and coil form attached thereto, a field magnet having an outer and an inner pole piece for said moving coil, a centering spider positioned interiorly of said diaphragm and coil and secured to said inner pole piece, means for attaching external circuit conductors to said coil form including terminal clips, and a securing strip encircling said coil form for securing said clips in place on said form.

2. The combination with a dynamic loud speaker diaphragm, of a cylindrical coil form and an inside centering spider attached to said diaphragm, means for connecting an external circuit conductor to said form comprising a metallic clip having a segmental flange conforming circumferentially to the shape of said form and provided with an angular terminal portion outwardly extending therefrom, and a securing strip encircling said form and said flange portion for holding said clip in place on said form.

3. The combination with a moving coil form for a sound translating device, of a sub-assembly terminal structure therefor comprising an elongated securing strip of insulating material, spaced metallic terminal clips mounted on and secured to said strip, said strip being circumferentially fastened to said coil form.

4. In a dynamic loud speaker having a voice coil and a voice coil form, a terminal clip for the voice coil, said terminal clip being provided with a segmental flange and upturned fingers on said flange, and a securing strip having apertures cooperating with said fingers for securing said terminal clips in place on said coil form.

5. The combination with a voice coil form for a sound translating device, of a sub-assembly terminal structure therefor comprising a single strip of fibrous material wrapped about said form, voice coil terminal clips each having a soldering lug, and integral means on said clips for fastening said clips in place along said strip comprising deformable projections and cooperating means on the strip to interlock with said projections.

6. In combination with a dynamic sound translating device having a voice coil form, a terminal structure for said coil form comprising an insulating strip having terminal positioning means along said strips and being fastened circumferentially to said coil form, a p ty f m tall c terminal clips secured to said strip in spaced relation and having portions adapted to cooperate with said positioning means to secure said clips to the strip.

7. In a dynamic sound translating device having a voice coil form provided with spaced apertures, a voice coil terminal clip having a flange and an extending soldering portion, means for securing said clip to said coil form comprising projections on said clips extending into cooperative relation with said apertures in said coil form.

8. As an article of manufacture, a terminal clip for a circular voice coil form in a dynamic speaker having a segmental flange portion for engaging the surface of said form, a second integral portion, to which a lead may be aflixed extending angularly from the first named portion, and a third integral portion extending angularly from the first named portion, and circumferential binding means cooperating with said last named portion for securing said clip in adjusted position on said coil form.

M. LEE MCMURTREY. DAVID H. CUNNINGHAM. 

